Bieberdorf F A, Chernick S S, Scow R O
J Clin Invest. 1970 Sep;49(9):1685-93. doi: 10.1172/JCI106386.
The metabolism of FFA and ketone bodies was studied in fasted rats by infusing at a constant rate tracer amounts of FFA-(3)H, beta-hydroxybutyrate-(14)C or acetoacetate-(14)C for periods up to 2 hr. Blood that was removed for analyses was replaced by continuous transfusion. The rates of turnover of FFA, beta-hydroxybutyrate, and acetoacetate in rats fasted for 2 days were, respectively, 3.2, 5.6, and 2.5 mumoles/100 g body weight per min. Infusion of mannoheptulose with anti-insulin serum increased plasma glucose, FFA, and ketone body concentrations and decreased the specific activity of plasma FFA. Injection of insulin (20 mU i.v.) decreased almost simultaneously plasma glucose, FFA, and ketone body concentrations and increased the specific activity of FFA, but it did not affect the plasma concentration of FFA-(3)H. The findings indicate that insulin deprivation increased and insulin injection decreased the release of FFA from body tissues in fasting rats. The plasma FFA concentration in fasting rats was increased by infusing chylomicrons and heparin, but this had very little effect on either plasma ketone body or glucose concentrations. Insulin injection (20 mU i.v.) lowered the plasma ketone body concentration in these animals. Studies using beta-hydroxybutyrate-(14)C showed that insulin (50 mU i.v.) decreased ketogenesis in the presence of a sustained high plasma FFA concentration and had no effect on uptake of circulating ketone bodies. The results indicate that plasma FFA concentration is not the sole determinant of plasma ketone body concentration and that insulin can suppress ketone body production through some means other than lowering plasma FFA concentration.
通过以恒定速率输注示踪量的FFA-(3)H、β-羟基丁酸-(14)C或乙酰乙酸-(14)C长达2小时，研究了禁食大鼠中游离脂肪酸（FFA）和酮体的代谢。用于分析而采集的血液通过连续输血进行补充。禁食2天的大鼠中，FFA、β-羟基丁酸和乙酰乙酸的周转速率分别为每分钟3.2、5.6和2.5微摩尔/100克体重。输注甘露庚酮糖和抗胰岛素血清会增加血浆葡萄糖、FFA和酮体浓度，并降低血浆FFA的比活性。静脉注射胰岛素（20 mU）几乎同时降低血浆葡萄糖、FFA和酮体浓度，并增加FFA的比活性，但不影响血浆FFA-(3)H的浓度。这些发现表明，在禁食大鼠中，胰岛素缺乏会增加而注射胰岛素会减少机体组织中FFA的释放。通过输注乳糜微粒和肝素可使禁食大鼠的血浆FFA浓度升高，但这对血浆酮体或葡萄糖浓度的影响很小。静脉注射胰岛素（20 mU）可降低这些动物的血浆酮体浓度。使用β-羟基丁酸-(14)C的研究表明，在血浆FFA浓度持续较高的情况下，胰岛素（50 mU静脉注射）可减少酮体生成，且对循环酮体的摄取没有影响。结果表明，血浆FFA浓度不是血浆酮体浓度的唯一决定因素，胰岛素可通过降低血浆FFA浓度以外的其他方式抑制酮体生成。
